What does "swinging a compass" refer to?

"Swinging a compass" refers specifically to the process of adjusting the compass's magnets to reduce compass deviation. This procedure is critical for ensuring accurate heading information. The compass can be influenced by magnetic fields generated by the aircraft itself, including effects from electrical equipment, metal structures, and other onboard components.

During the swinging process, the aircraft is typically rotated in a circular motion at a designated location, allowing the technician to observe how the compass reacts and records heading readings. Any discrepancies from magnetic North are noted, and adjustments to the compass’s magnets or compensators can be made to realign the readings accurately. This results in a more reliable navigation tool, essential for safe and effective flight operations.

Calibration and testing functions, mentioned in the other options, serve different purposes and do not pertain directly to the principle of adjusting the compass itself to negate deviation caused by external magnetic influences. Thus, aligning the compass by swinging it is a specific and necessary task in maintaining precision in navigation.